Field of the Invention
The present invention relates to an electrochemical device that utilizes lithium ion pre-doping.
Description of the Related Art
In recent years, electrochemical devices such as capacitors are utilized as systems for storing clean energy produced by solar generation, wind generation, etc., and also as main power supplies or auxiliary power supplies for automobiles, hybrid electric vehicles, and so on. In the above, electrical double-layer capacitors offer high output but their capacitance is low, while batteries are high in capacitance but their output is low. Accordingly, lithium ion capacitors whose negative electrode uses a material capable of occluding lithium ions, and which therefore boast higher capacitance than electrical double-layer capacitors and longer service life than batteries, are fast replacing batteries.
On the other hand, lithium ion capacitors require a step called “pre-doping” where lithium ions are doped into the negative electrode beforehand, as is the case with the invention described in Patent Literature 1, for example, and this can lead to lower productivity.
Accordingly, Patent Literature 2 describes a technology, for example, whereby a lithium ion supply source is placed in a positive electrode gap part or negative electrode gap part, for instance, so as to dope lithium ions more quickly into the negative electrode, thereby shortening the pre-doping time.